This application is a 371 of International Patent Application No. PCT/EP96/00716, filed Feb. 19, 1996, which claims priority from application EPO 9521951.1, Jul. 14, 1995 and application EPO 95200390.3, filed Feb. 17, 1995.
The present invention relates to the identification of the High Mobility Group (HMG) protein gene family as a family of genes frequently associated with aberrant cell growth as found in a variety of both benign and malignant tumors. The invention in particular relates to the identification of a member of the HMG gene family as the broadly acting chromosome 12 breakpoint region gene involved in a number of tumors, including but not limited to the mesenchymal tumors hamartomas (e.g. breast and lung), lipomas, pleomorphic salivary gland adenomas, uterine leiomyomas, angiomyxomas, fibroadenomas of the breast, polyps of the endometrium, atherosclerotic plaques, and other benign tumors as well as various malignant tumors, including but not limited to sarcomas (e.g. rhabdomyosarcoma, osteosarcoma) and carcinomas (e.g. of breast, lung, skin, thyroid), as well as leukemias and lymphomas. The invention also relates to another member of the HMG gene family that was found to be implicated in breaks in chromosome 6.
Furthermore, the invention concerns the identification of members of the LIM protein family as another type of tumor-type specific breakpoint region genes and frequent fusion partners of the HMG genes in these tumors. The LPP (Lipoma-Preferred Partner) gene of this family is found to be specific for lipomas. The invention relates in particular to the use of the members of the HMG and LIM gene family and their derivatives in diagnosis and therapy.
Multiple independent cytogenetic studies have firmly implicated region q13-q15 of chromosome 12 in a variety of benign and malignant solid tumor types. Among benign solid tumors, involvement of 12q13-q15 is frequently observed in benign adipose tissue tumors [1], uterine leiomyomas [2, 3], and pleomorphic adenomas of the salivary glands [4, 5]. Involvement of the same region has also been reported for endometrial polyps [6, 7] for hemangio-pericytoma [8], and for chondromatous tumors [9, 10, 11, 12]. Recently, the involvement of chromosome 12q13-q15 was reported in pulmonary chondroid hamartoma [13, 14]. Finally, several case reports of solid tumors with involvement of chromosome region 12q13-q15 have been published; e.g. tumors of the breast [15, 16), diffuse astrocytomas [17], and a giant-cell tumor of the bone [18]. Malignant tumor types with recurrent aberrations in 12q13-q15 include myxoid liposarcoma [19], soft tissue clear-cell sarcoma [20, 21, 22], and a subgroup of rhabdomyosarcoma [23].
Although these studies indicated that the same cytogenetic region of chromosome 12 is often involved in chromosome aberrations, like translocations, in these solid tumors, the precise nature of the chromosome 12 breakpoints in the various tumors is still not known. Neither was it established which genes are affected directly by the translocations.
In previous physical mapping studies [39], the chromosome 12q breakpoints in lipoma, pleomorphic salivary gland adenoma, and uterine leiomyoma were mapped between locus D12S8 and the CHOP gene and it was shown that D12S8 is located distal to CHOP. Recently, it was also found by FISH analysis that the chromosome 12q breakpoints in a hamartoma of the breast, an angiomyxoma and multiple pulmonary chondroid hamartomas are mapping within this DNA interval. In an effort to molecularly clone the genes affected by the chromosome 12q13-q15 aberrations in the various tumors, the present inventors chose directional chromosome walking as a structural approach to define the DNA region encompassing these breakpoints.
As a starting point for chromosome walking, locus D12S8 was used. During these walking studies, it was shown that the chromosomal breakpoints as present in a number of uterine leiomyoma-derived cell lines are clustered within a 445 kb chromosomal segment which has been designated Uterine Leiomyoma Cluster Region on chromosome 12 (ULCR12) [24]. Subsequently, it was found that a 1.7 Mb region on chromosome 12 encompasses the chromosome 12 breakpoints of uterine leiomyoma-, lipoma-, and salivary gland adenoma-cells, with the breakpoint cluster regions of the various tumor types overlapping [25, xe2x80x9cANNEX 1xe2x80x9d]. This 1.7 Mb region on the long arm of chromosome 12, which contains ULCR12 obviously, was designated Multiple Aberration Region (MAR) to reflect this feature. In a regional fine mapping study, MAR was recently assigned to 12q15.
It has thus been found that essentially all breakpoints of chromosome 12 map in a 1.7 Mb region indicated herein as the xe2x80x9cMultiple Aberration Regionxe2x80x9d or MAR. Further research revealed that in this region a member of the High Mobility Group gene family, the HMGI-C gene, can be identified as a postulated multi-tumor aberrant growth gene (MAG). The same applies to members of the LIM family which are also found to be involved in chromosome aberrations. Of these the chromosome 3-derived Lipoma-Preferred Partner (LPP) gene is particularly implicated in lipomas.
LIM proteins are proteins carrying cystein-rich zinc-binding domains, so-called LIM domains. They are involved in protein-protein interactions [for a review see ref. 80]. One of the members of the protein family is the now disclosed LPP protein mapping at chromosome 3.
According to the present invention the aberrations in the HMGI-C gene on chromosome 12 and the LPP gene on chromosome 3 have been used as a model to reveal the more general concept of the involvement of members of the HMG and LIM gene families in both benign and malignant tumors. To demonstrate that there exists a more general concept of gene families, which, when affected by chromosome rearrangements, lead to a particular group of tumor growth, the present inventors demonstrated that the HMGI(Y) gene, which is a member of the HMG family, is involved in breaks in chromosome 6.
Although both the HMG and LIM gene families are known per se, up till the present invention the correlation between these families and tumor inducing chromosome aberrations, like translocations, deletions, insertions and inversions, has not been anticipated. Furthermore, until now it was not previously demonstrated that alterations in the physiological expression level of the members of the gene family are probably also implicated in tumor development. According to the invention it was demonstrated that in normal adult cells the expression level of the HMGI-C gene is practically undetectable, whereas in aberrantly growing cells the expression level is significantly increased.
Based on these insights the present invention now provides for the members of the gene families or derivatives thereof in isolated form and their use in diagnostic and therapeutic applications. Furthermore the knowledge on the location and nucleotide sequence of the genes may be used to study their rearrangements or expression and to identify a possible increase or decrease in their expression level and the effects thereof on cell growth. Based on this information diagnostic tests or therapeutic treatments may be designed.